/*
	Perlin simplex noise cube3 
*/

using System;

namespace IrrlichtNETCP.Extensions.Other
{
    public static class PerlinSimplexNoise
    {
        #region Initizalize grad3

        private static int[][] grad3 = {
                                           new int[]{1,1,0},
                                           new int[]{-1,1,0},
                                           new int[]{1,-1,0},
                                           new int[]{-1,-1,0},
                                           new int[]{1,0,1},
                                           new int[]{-1,0,1},
                                           new int[]{1,0,-1},
                                           new int[]{-1,0,-1},
                                           new int[]{0,1,1},
                                           new int[]{0,-1,1},
                                           new int[]{0,1,-1},
                                           new int[]{0,-1,-1}
                                       };

        #endregion

        #region Initizalize grad4

        private static int[][] grad4 = {
                                           new int[]{0,1,1,1},
                                           new int[]{0,1,1,-1},
                                           new int[]{0,1,-1,1},
                                           new int[]{0,1,-1,-1},
                                           new int[]{0,-1,1,1},
                                           new int[]{0,-1,1,-1},
                                           new int[]{0,-1,-1,1},
                                           new int[]{0,-1,-1,-1},
                                           new int[]{1,0,1,1},
                                           new int[]{1,0,1,-1},
                                           new int[]{1,0,-1,1},
                                           new int[]{1,0,-1,-1},
                                           new int[]{-1,0,1,1},
                                           new int[]{-1,0,1,-1},
                                           new int[]{-1,0,-1,1},
                                           new int[]{-1,0,-1,-1},
                                           new int[]{1,1,0,1},
                                           new int[]{1,1,0,-1},
                                           new int[]{1,-1,0,1},
                                           new int[]{1,-1,0,-1},
                                           new int[]{-1,1,0,1},
                                           new int[]{-1,1,0,-1},
                                           new int[]{-1,-1,0,1},
                                           new int[]{-1,-1,0,-1},
                                           new int[]{1,1,1,0},
                                           new int[]{1,1,-1,0},
                                           new int[]{1,-1,1,0},
                                           new int[]{1,-1,-1,0},
                                           new int[]{-1,1,1,0},
                                           new int[]{-1,1,-1,0},
                                           new int[]{-1,-1,1,0},
                                           new int[]{-1,-1,-1,0}
                                       };

        #endregion
       
        // A lookup table to traverse the simplex around a given point in 4D.
        // Details can be found where this table is used, in the 4D noise method.
        private static int[][] simplex = {
            new int[]{0,1,2,3},new int[]{0,1,3,2},new int[]{0,0,0,0},new int[]{0,2,3,1},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{1,2,3,0},
            new int[]{0,2,1,3},new int[]{0,0,0,0},new int[]{0,3,1,2},new int[]{0,3,2,1},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{1,3,2,0},
            new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},
            new int[]{1,2,0,3},new int[]{0,0,0,0},new int[]{1,3,0,2},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{2,3,0,1},new int[]{2,3,1,0},
            new int[]{1,0,2,3},new int[]{1,0,3,2},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{2,0,3,1},new int[]{0,0,0,0},new int[]{2,1,3,0},
            new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},
            new int[]{2,0,1,3},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{3,0,1,2},new int[]{3,0,2,1},new int[]{0,0,0,0},new int[]{3,1,2,0},
            new int[]{2,1,0,3},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{0,0,0,0},new int[]{3,1,0,2},new int[]{0,0,0,0},new int[]{3,2,0,1},new int[]{3,2,1,0}
                                         };
       
        #region Init p

        private static int[] p = {151,160,137,91,90,15,131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23,
190, 6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,
88,237,149,56,87,174,20,125,136,171,168, 68,175,74,165,71,134,139,48,27,166,
77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,
102,143,54, 65,25,63,161, 1,216,80,73,209,76,132,187,208, 89,18,169,200,196,
135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,250,124,123,
5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,
223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167, 43,172,9,
129,22,39,253, 19,98,108,110,79,113,224,232,178,185, 112,104,218,246,97,228,
251,34,242,193,238,210,144,12,191,179,162,241, 81,51,145,235,249,14,239,107,
49,192,214, 31,181,199,106,157,184, 84,204,176,115,121,50,45,127, 4,150,254,
138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180};

        #endregion
       
       
        // To remove the need for index wrapping, float the permutation table length
        private static int[] perm = new int[512];
       
        /// <summary>
        /// Initializes the <see cref="PerlinSimplexNoise"/> class.
        /// </summary>
        /// <author>Sjef van Leeuwen 3-3-2007 18:27</author>
        static PerlinSimplexNoise()
        {
            for(int i=0; i<512; i++) perm[i]=p[i & 255];
        }
   
         // This method is a *lot* faster than using (int)Math.floor(x)
        private static int fastfloor(float x)
        {
            return x>0 ? (int)x : (int)x-1;
        }
       
        private static float dot(int[] g, float x, float y)
        {
            return g[0]*x + g[1]*y;
        }

        private static float dot(int[] g, float x, float y, float z)
        {
            return g[0]*x + g[1]*y + g[2]*z;
        }

        private static float dot(int[] g, float x, float y, float z, float w)
        {
            return g[0]*x + g[1]*y + g[2]*z + g[3]*w;
        }


        /// <summary>
        /// 3D Simplex noise.
        /// </summary>
        /// <param name="xin">The xin.</param>
        /// <param name="yin">The yin.</param>
        /// <param name="zin">The zin.</param>
        /// <returns></returns>
        /// <author>Sjef van Leeuwen 3-3-2007 18:44</author>
        public static float noise(float xin, float yin, float zin)
        {
            float n0, n1, n2, n3; // Noise contributions from the four corners
            // Skew the input space to determine which simplex cell we're in
            float F3 = 1.0f / 3.0f;
            float s = (xin + yin + zin) * F3; // Very nice and simple skew factor for 3D
            int i = fastfloor(xin + s);
            int j = fastfloor(yin + s);
            int k = fastfloor(zin + s);
            float G3 = 1.0f / 6.0f; // Very nice and simple unskew factor, too
            float t = (i + j + k) * G3;
            float X0 = i - t; // Unskew the cell origin back to (x,y,z) space
            float Y0 = j - t;
            float Z0 = k - t;
            float x0 = xin - X0; // The x,y,z distances from the cell origin
            float y0 = yin - Y0;
            float z0 = zin - Z0;
            // For the 3D case, the simplex shape is a slightly irregular tetrahedron.
            // Determine which simplex we are in.
            int i1, j1, k1; // Offsets for second corner of simplex in (i,j,k) coords
            int i2, j2, k2; // Offsets for third corner of simplex in (i,j,k) coords
            if (x0 >= y0)
            {
                if (y0 >= z0)
                {
                    i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 1; k2 = 0;
                } // X Y Z order
                else if (x0 >= z0)
                {
                    i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 0; k2 = 1;
                } // X Z Y order
                else
                {
                    i1 = 0; j1 = 0; k1 = 1; i2 = 1; j2 = 0; k2 = 1;
                } // Z X Y order
            }
            else
            { // x0<y0
                if (y0 < z0)
                {
                    i1 = 0; j1 = 0; k1 = 1; i2 = 0; j2 = 1; k2 = 1;
                } // Z Y X order
                else if (x0 < z0)
                {
                    i1 = 0; j1 = 1; k1 = 0; i2 = 0; j2 = 1; k2 = 1;
                } // Y Z X order
                else
                {
                    i1 = 0; j1 = 1; k1 = 0; i2 = 1; j2 = 1; k2 = 0;
                } // Y X Z order
            }
            // A step of (1,0,0) in (i,j,k) means a step of (1-c,-c,-c) in (x,y,z),
            // a step of (0,1,0) in (i,j,k) means a step of (-c,1-c,-c) in (x,y,z), and
            // a step of (0,0,1) in (i,j,k) means a step of (-c,-c,1-c) in (x,y,z), where
            // c = 1/6.
            float x1 = x0 - i1 + G3; // Offsets for second corner in (x,y,z) coords
            float y1 = y0 - j1 + G3;
            float z1 = z0 - k1 + G3;
            float x2 = x0 - i2 + 2.0f * G3; // Offsets for third corner in (x,y,z) coords
            float y2 = y0 - j2 + 2.0f * G3;
            float z2 = z0 - k2 + 2.0f * G3;
            float x3 = x0 - 1.0f + 3.0f * G3; // Offsets for last corner in (x,y,z) coords
            float y3 = y0 - 1.0f + 3.0f * G3;
            float z3 = z0 - 1.0f + 3.0f * G3;
            // Work out the hashed gradient indices of the four simplex corners
            int ii = i & 255;
            int jj = j & 255;
            int kk = k & 255;
            int gi0 = perm[ii + perm[jj + perm[kk]]] % 12;
            int gi1 = perm[ii + i1 + perm[jj + j1 + perm[kk + k1]]] % 12;
            int gi2 = perm[ii + i2 + perm[jj + j2 + perm[kk + k2]]] % 12;
            int gi3 = perm[ii + 1 + perm[jj + 1 + perm[kk + 1]]] % 12;
            // Calculate the contribution from the four corners
            float t0 = 0.6f - x0 * x0 - y0 * y0 - z0 * z0;
            if (t0 < 0) n0 = 0.0f;
            else
            {
                t0 *= t0;
                n0 = t0 * t0 * dot(grad3[gi0], x0, y0, z0);
            }
            float t1 = 0.6f - x1 * x1 - y1 * y1 - z1 * z1;
            if (t1 < 0) n1 = 0.0f;
            else
            {
                t1 *= t1;
                n1 = t1 * t1 * dot(grad3[gi1], x1, y1, z1);
            }
            float t2 = 0.6f - x2 * x2 - y2 * y2 - z2 * z2;
            if (t2 < 0) n2 = 0.0f;
            else
            {
                t2 *= t2;
                n2 = t2 * t2 * dot(grad3[gi2], x2, y2, z2);
            }
            float t3 = 0.6f - x3 * x3 - y3 * y3 - z3 * z3;
            if (t3 < 0) n3 = 0.0f;
            else
            {
                t3 *= t3;
                n3 = t3 * t3 * dot(grad3[gi3], x3, y3, z3);
            }
            // Add contributions from each corner to get the final noise value.
            // The result is scaled to stay just inside [-1,1]
            return 32.0f * (n0 + n1 + n2 + n3);
        }

        // 2D simplex noise
        public static float noise(float xin, float yin)
        {
            float n0, n1, n2; // Noise contributions from the three corners
            // Skew the input space to determine which simplex cell we're in
            float F2 = (float)(0.5*(Math.Sqrt(3.0)-1.0));
            float s = (xin+yin)*F2; // Hairy factor for 2D
            int i = fastfloor(xin+s);
            int j = fastfloor(yin+s);
            float G2 = (float)((3.0-Math.Sqrt(3.0))/6.0);
            float t = (i+j)*G2;
            float X0 = i-t; // Unskew the cell origin back to (x,y) space
            float Y0 = j-t;
            float x0 = xin-X0; // The x,y distances from the cell origin
            float y0 = yin-Y0;
            // For the 2D case, the simplex shape is an equilateral triangle.
            // Determine which simplex we are in.
            int i1, j1; // Offsets for second (middle) corner of simplex in (i,j) coords
            if(x0>y0)
            {
                i1=1; j1=0;
            } // lower triangle, XY order: (0,0)->(1,0)->(1,1)
            else
            {
                i1=0; j1=1;
            } // upper triangle, YX order: (0,0)->(0,1)->(1,1)
            // A step of (1,0) in (i,j) means a step of (1-c,-c) in (x,y), and
            // a step of (0,1) in (i,j) means a step of (-c,1-c) in (x,y), where
            // c = (3-sqrt(3))/6
            float x1 = x0 - i1 + G2; // Offsets for middle corner in (x,y) unskewed coords
            float y1 = y0 - j1 + G2;
            float x2 = x0 - 1.0f + 2.0f * G2; // Offsets for last corner in (x,y) unskewed coords
            float y2 = y0 - 1.0f + 2.0f * G2;
            // Work out the hashed gradient indices of the three simplex corners
            int ii = i & 255;
            int jj = j & 255;
            int gi0 = perm[ii+perm[jj]] % 12;
            int gi1 = perm[ii+i1+perm[jj+j1]] % 12;
            int gi2 = perm[ii+1+perm[jj+1]] % 12;
            // Calculate the contribution from the three corners
            float t0 = 0.5f - x0*x0-y0*y0;
            if(t0<0)
                n0 = 0.0f;
            else
            {
                t0 *= t0;
                n0 = t0 * t0 * dot(grad3[gi0], x0, y0); // (x,y) of grad3 used for 2D gradient
            }
            float t1 = 0.5f - x1*x1-y1*y1;
            if(t1<0)
                n1 = 0.0f;
            else
            {
                t1 *= t1;
                n1 = t1 * t1 * dot(grad3[gi1], x1, y1);
            }
            float t2 = 0.5f - x2*x2-y2*y2;
            if(t2<0)
                n2 = 0.0f;
            else
            {
                t2 *= t2;
                n2 = t2 * t2 * dot(grad3[gi2], x2, y2);
            }
            // Add contributions from each corner to get the final noise value.
            // The result is scaled to return values in the interval [-1,1].
            return 70.0f * (n0 + n1 + n2);
        }
    }
}